In order to prevent degradation in freshness or taste due to the oxidization of contents of a container filled with contents such as a beverage can, an undercover gassing method has been widely used in a can manufacturing process. As illustrated in FIG. 10, a gas is replaced by blowing a replacement gas toward a gap between a can lid and a can body opening directly before covering an opening of a can body 30 by a can lid 33 between a gas turret 1 and a seaming turret 2. However, since the undercover gassing method has poor replacement efficiency, there has been a noticeable increasing flow amount of the replacement gas used to attain a predetermined replacement rate or more with the recent trend of an increase in speed of manufacturing lines and the variety of contents. Further, the amount of a liquid spilling from the can also tends to increase with an increase in replacement gas flow amount.
In order to improve the replacement efficiency of the undercover gassing method, there have been various attempts from the past. For example, proposed are a configuration in which a replacement gas passageway toward a replacement nozzle is formed in a large size (to form a so-called buffer) and a blowout hole group of the nozzle is provided in three stages in the longitudinal direction as a first gas jet flow hole through which a replacement gas blows to a flange of a can lid, a second gas jet flow hole through which the replacement gas blows to a space below the lid in a direction perpendicular to the can, and a third gas jet flow hole through which the replacement gas blows to a wall portion below a can opening edge (Patent Document 1), a configuration in which a branch body is provided at a center portion of a replacement gas jet passageway so as to branch a gas flow left and right and left and right nozzles are formed so that replacement gases jetted from the pair of nozzles collide with each other at a center portion of an upper space inside the can so as to direct the replacement gas to a liquid surface of a head space of the can (Patent Document 2), a configuration in which replacement gases blowing from a pair of left and right blowout ports collide with each other on the substantially straight collision region (Patent Documents 3 and 4), and the like. FIGS. 11 and 12 illustrate an example of a nozzle body 50 of the prior art provided in a pocket of a gas turret as illustrated in the Patent Document 3. Left and right branched replacement gas passageways 51a and 51b are divided by a wind direction adjustment plate 52 so as to form opposing blowout ports 53a and 53b, and the replacement gases symmetrically blow from the blowout ports to a gap between the can body and the can lid. However, in the conventional nozzle body, since can lid transfer fingers 55 are provided on the gas turret body at the same level position as that of the nozzle body so as to be positioned at the outside of both end portions as illustrated in the front view of the pocket of the gas turret of FIG. 12, an angle θ between outermost walls 54a and 54b of the nozzle blowout ports may be set to only 90° or less (normally, 80°).